December 2004NASA Electronic Parts and Packaging Program Effects of Low Temperature and Thermal Cycling on Switching Characteristics of 2N3811 PNP and LM394 NPN Transistors Richard Patte
Trang 1December 2004
NASA Electronic Parts and Packaging Program
Effects of Low Temperature and Thermal Cycling on Switching Characteristics of 2N3811 PNP and LM394 NPN Transistors
Richard Patterson, NASA Glenn Research Center Ahmad Hammoud, QSS Group, Inc / NASA GRC Malik Elbuluk, University of Akron
Scope
Certain NASA space missions require electronics to operate reliably and efficiently in harsh environments Extreme temperatures constitute one of such environments that are typically encountered in planetary exploration and deep space applications Little is known about the performance of many electronic components under extreme temperatures; in particular cryogenic environments In this work, the performance of two types of bipolar transistors was evaluated under low temperature and thermal cycling The investigations were carried out to establish a baseline on functionality and to determine suitability of these devices for use in space applications under cryogenic temperatures These devices were chosen because they are being considered by the NASA Jet Propulsion Laboratory (JPL) for use in electronic circuits on future space missions
Test Procedure
The devices investigated in this work comprised of Microsemi Lawrence 2N3811 PNP dual transistors and National Semiconductor LM394 NPN supermatch pair transistors Two devices of each type of transistor were examined for operation between -195 °C and +20 °C Performance characterization was obtained in terms of their switching characteristics, using a Sony/Tektronix 370A programmable curve tracer, at specific test temperatures Cold-restart capability, i.e power switched on while the devices were at a temperature of -195 °C, was also investigated A temperature rate of change of 10 °C per minute was used, and a soak time of at least 20 minutes was allowed at every test temperature The effects of thermal cycling under a wide temperature range on the operation of these transistors were also investigated The devices were exposed to a total
of 10 cycles between -195 °C and +100 °C at a temperature rate of 10 °C/minute Following the thermal cycling, measurements were then performed at the test temperatures of +20, -195, +100, and again at +20 °C Some of the manufacturer’s specifications for these bipolar transistors are shown in Table I [1-2]
Trang 2Table I Manufacturer’s specifications of bipolar transistors [1-2].
Test Results
Although two devices of each of the bipolar transistors were evaluated, data pertaining to only one of each type is presented due to the similarity in the results of the same type devices
Temperature Effects
Figure 1 shows the output characteristics of the 2N3811 PNP transistor at room
temperature was decreased below room temperature, the base current had to be increased
to maintain the collector current at a predetermined value In other words, the decrease in temperature resulted in a downward shift of the family curves The switching characteristics of this transistor at the extreme temperature of -195 °C are shown in Figure 2 It is important to note that in addition to the downshift of the switching curves
at the extreme temperature, larger step size was used in the base biasing current Such a behavior is an indicative of the decrease in the current gain of the transistor as temperature was decreased This effect of temperature on the transistor’s gain is clearly depicted in Figure 3
2
Trang 30 0 2 0 4 0 6 0 8 1
VC E ( V ) 0
0 0 0 2
0 0 0 4
0 0 0 6
0 0 0 8
0 0 1
I C
5 µ A
1 0 µ A
5 0 µ A
2 0 µ A
3 0 µ A
4 0 µ A
Fig 1 Characteristics of 2N3811 at 20 °C.
VC E ( V ) 0
0 0 0 2
0 0 0 4
0 0 0 6
0 0 0 8
0 0 1
I C
5 0 0
4 0 0
3 0 0
2 0 0
5 0
1 0 0
Fig 2 Characteristics of 2N3811 at -195 °C.
Trang 4- 2 0 0 - 1 5 0 - 1 0 0 - 5 0 0 5 0
T e m p e r a t u r e ( o C ) 0
1 0 0
2 0 0
3 0 0
V C E = 0 8 V
I B = 1 0 A
I B = 2 0 A
I B = 2 5 A
I B = 1 5 A
Figure 3 DC current gain of 2N3811 versus temperature
Similar to its PNP counterpart, the LM394 NPN transistor exhibited identical trend in its output characteristics with temperature, i.e a downward shift of the family curves as test temperature was decreased The output characteristics of this transistor at 20 °C and at -195 °C are shown in Figures 4 and 5, respectively, and the effect of temperature on its DC current gain is shown in Figure 6
0
0 0 0 4
0 0 0 8
0 0 1 2
0 0 1 6
0 0 2
I C
5 µ A
1 0 µ A
1 5 µ A
2 0 µ A
2 5 µ A
3 0 µ A
3 5 µ A , 4 0 µ A , 4 5 µ A , 5 0 µ A
Fig 4 Characteristics of LM394 at 20 °C.
V C E ( V ) 0
0 0 0 4
0 0 0 8
0 0 1 2
0 0 1 6
0 0 2
I C
5 0 µ A
5 0 0 µ A
4 0 0 µ A
3 0 0 µ A
2 0 0 µ A
1 0 0 µ A
Fig 5 Characteristics of LM394 at -195 °C.
4
Trang 5- 2 0 0 - 1 5 0 - 1 0 0 - 5 0 0 5 0
T e m p e r a t u r e ( o C ) 0
2 0 0
4 0 0
h F
VC E= 3 V
IB= 1 0 A
I B = 2 0 A
IB= 2 5 A
IB= 1 5 A
Figure 6 DC current gain of LM394 versus temperature
Cold Re-Start
Cold-restart capability of the 2N3811 PNP and the LM394 NPN transistors was investigated by allowing the devices to soak at -195 °C for 20 minutes without electrical bias Power was then applied to the device under test and the switching characteristics were recorded All transistors did perform cold start at -195 °C, and the results pertaining
to each device were similar to those obtained earlier at that temperature
Effects of Thermal Cycling
The effects of thermal cycling under a wide temperature range on the operation of the transistors were investigated by subjecting them to a total of 10 cycles between -195 °C and +100 °C at a temperature rate of 10 °C/minute Switching characteristics of each transistor were taken at +20 °C before cycling, and at -195, +100, and +20 °C after the thermal cycling Figures 7 and 8 depict the switching characteristics of the 2N3811 and LM394 transistor, respectively No major changes were observed, for either device, in their switching characteristics due to this limited cycling This is evident from the similarity in the switching curves taken at +20 °C prior to and after completion of the thermal cycling This limited thermal cycling also appeared to have no effect on the structural integrity of these transistors as none underwent any structural deterioration or packaging damage
Trang 60 0 2 0 4 0 6 0 8 1
V C E ( V ) 0
0 0 0 2
0 0 0 4
0 0 0 6
0 0 0 8
0 0 1
I C
5 µ A
1 0 µ A
5 0 µ A
2 0 µ A
3 0 µ A
4 0 µ A
Pre-cycling @ test temperature of 20 °C.
VC E ( V ) 0
0 0 0 2
0 0 0 4
0 0 0 6
0 0 0 8
0 0 1
I C
5 µ A
1 0 µ A
5 0 µ A
2 0 µ A
3 0 µ A
4 0 µ A
Post-cycling @ test temperature of +100 °C.
V C E ( V ) 0
0 0 0 2
0 0 0 4
0 0 0 6
0 0 0 8
0 0 1
I C
5 0 µ A
1 0 0 µ A
5 0 0 µ A
2 0 0 µ A
3 0 0 µ A
4 0 0 µ A
Post-cycling @ test temperature of -195 °C.
V C E ( V ) 0
0 0 0 2
0 0 0 4
0 0 0 6
0 0 0 8
0 0 1
I C
5 µ A
1 0 µ A
5 0 µ A
2 0 µ A
3 0 µ A
4 0 µ A
Post-cycling @ test temperature of 20 °C.
Figure 7 Switching characteristics of 2N3811 transistor at selected pre and post-cycling
temperatures
Trang 70 1 2 3 4 5
0
0 0 0 4
0 0 0 8
0 0 1 2
0 0 1 6
0 0 2
I C
5 µ A
1 0 µ A
1 5 µ A
2 0 µ A
2 5 µ A
3 0 µ A
3 5 µ A , 4 0 µ A , 4 5 µ A , 5 0 µ A
Pre-cycling @ test temperature of 20 °C.
0
0 0 0 4
0 0 0 8
0 0 1 2
0 0 1 6
0 0 2
I C
5 µ A
1 0 µ A
1 5 µ A
2 0 µ A
3 5 µ A , 4 0 µ A , 4 5 µ A , 5 0 µ A
2 5 µ A , 3 0 µ A
Post-cycling @ test temperature of +100 °C.
V C E ( V ) 0
0 0 0 4
0 0 0 8
0 0 1 2
0 0 1 6
0 0 2
I C
5 0 µ A
5 0 0 µ A
4 0 0 µ A
3 0 0 µ A
2 0 0 µ A
1 0 0 µ A
Post-cycling @ test temperature of -195 °C.
0
0 0 0 4
0 0 0 8
0 0 1 2
0 0 1 6
0 0 2
I C
5 µ A
1 0 µ A
1 5 µ A
2 0 µ A
2 5 µ A
3 0 µ A
3 5 µ A , 4 0 µ A , 4 5 µ A , 5 0 µ A
Post-cycling @ test temperature of 20 °C.
Trang 8Figure 8 Switching characteristics of LM394 transistor at selected pre and post-cycling
temperatures
Trang 9Microsemi Lawrence 2N3811 PNP dual transistors and National Semiconductor LM394 NPN supermatch pair transistors were evaluated under extreme temperatures Two devices of each type of transistor were examined for operation between -195 °C and +20
°C Performance characterization was obtained in terms of their switching characteristics and DC current gain The effects of thermal cycling under a wide temperature range on the operation of the transistors and cold-restart capability were also investigated Although the DC current gain exhibited appreciable drop as the test temperature was decreased, both types of devices were able to maintain operation between -195 °C and +20 °C The limited thermal cycling performed on the devices had no effect on their performance, and all transistors were able to cold start at -195 °C Further testing under long term cycling is required to fully establish the reliability of these devices and to determine their suitability for extended use in extreme temperature environments
References
Sheet, 120101
Data Sheet TL/H/9241, December 1994
Acknowledgements
This work was performed under the NASA Glenn Research Center GESS Contract # NAS3-00145 Funding was provided by the NASA Electronic Parts and Packaging (NEPP) Program